From 28884e1f4f97ed8cdde0c7ebcc1f20698c923963 Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Sun, 30 Jun 2024 19:33:18 -0400
Subject: [PATCH] xo-expression: refactor: use GlobalEnv for
 MachPipeline::global_env

---
 include/xo/expression/Environment.hpp |  5 ++--
 include/xo/expression/GlobalEnv.hpp   | 34 +++++++++++++++------------
 include/xo/expression/LocalEnv.hpp    |  2 +-
 3 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/include/xo/expression/Environment.hpp b/include/xo/expression/Environment.hpp
index 834366c7..6fec9b32 100644
--- a/include/xo/expression/Environment.hpp
+++ b/include/xo/expression/Environment.hpp
@@ -12,9 +12,10 @@ namespace xo {
     namespace ast {
         class Environment : public ref::Refcount {
         public:
-            /** lookup variable-expression @p vname in this environment
+            /** lookup variable-expression @p vname in this environment.
+             *  returns llvm::Value representing code that produces a value for vname
              **/
-            virtual ref::brw<Variable> lookup_var(const std::string & vname) const = 0;
+            virtual ref::brw<Expression> lookup_var(const std::string & vname) const = 0;
         };
     } /*namespace ast*/
 } /*namespace xo*/
diff --git a/include/xo/expression/GlobalEnv.hpp b/include/xo/expression/GlobalEnv.hpp
index 223fc9df..fbc9ef9c 100644
--- a/include/xo/expression/GlobalEnv.hpp
+++ b/include/xo/expression/GlobalEnv.hpp
@@ -12,32 +12,36 @@ namespace xo {
     namespace ast {
         class GlobalEnv : public Environment {
         public:
-            ref::brw<Variable> require_global(ref::brw<Variable> var) {
-                const std::string & vname = var->name();
+            /** create instance.  Probably only need one of these **/
+            static ref::rp<GlobalEnv> make() { return new GlobalEnv(); }
 
-                auto ix = var_map_.find(vname);
-
-                if (ix == var_map_.end()) {
-                    var_map_[vname] = var.get();
-                    return var;
-                } else {
-                    return ix->second;
-                }
+            ref::brw<Expression> require_global(const std::string & vname,
+                                                ref::brw<Expression> expr) {
+                global_map_[vname] = expr.get();
+                return expr;
             } /*require_global*/
 
             // ----- Environment -----
 
-            virtual ref::brw<Variable> lookup_var(const std::string & vname) const {
-                auto ix = var_map_.find(vname);
+            virtual ref::brw<Expression> lookup_var(const std::string & vname) const {
+                auto ix = global_map_.find(vname);
 
-                if (ix == var_map_.end())
-                    return ref::brw<Variable>::from_native(nullptr);
+                if (ix == global_map_.end()) {
+                    /* not found */
+                    return ref::brw<Expression>::from_native(nullptr);
+                }
 
                 return ix->second;
             }
 
         private:
-            std::map<std::string, ref::rp<Variable>> var_map_;
+            GlobalEnv() = default;
+
+        private:
+            /* for assignable globals,  need to allocate memory
+             * addresses for these.
+             */
+            std::map<std::string, ref::rp<Expression>> global_map_;
         };
     } /*namespace ast*/
 } /*namespace xo*/
diff --git a/include/xo/expression/LocalEnv.hpp b/include/xo/expression/LocalEnv.hpp
index 7f5f12dd..b206bddf 100644
--- a/include/xo/expression/LocalEnv.hpp
+++ b/include/xo/expression/LocalEnv.hpp
@@ -38,7 +38,7 @@ namespace xo {
 
             // ----- Environment -----
 
-            virtual ref::brw<Variable> lookup_var(const std::string & target) const override {
+            virtual ref::brw<Expression> lookup_var(const std::string & target) const override {
                 for (const auto & arg : argv_) {
                     if (arg->name() == target)
                         return arg;